Musty odor in piano

[Robert Goodale]

I would agree with Mr. Blees in that the FIRST thing you need to do is take the
piano completely apart and give it a complete cleaning.  Vacuum it out, blow it
with compresset air, wipe out any stained areas, clean under the keys, and
clean/blow out the lower back area where dirt likes to accumulate at the bottom
of the soundboard.  Only then can you really attack the odor issue.  You never
know-- there might even be something dead in there.

Rob Goodale, RPT